(1) Field of the Invention
This invention relates to cotton processing and more specifically to the separation of trash from cotton prior to ginning.
(2) Description of the Prior Art
The grade that a sample of cotton is assigned is very important in determining the value of the cotton. An important consideration in the grading of cotton is its cleanliness. Through the years, many methods of cleaning cotton have been tried, including methods which attempt to remove trash, including burrs, sticks, etc. from the seed cotton. It is desirable to reclaim cotton which might be removed with the trash. The most effective manner of cleaning cotton has been a three or four step process in which the same procedure is repeated until the trash which is excluded has little reclaimable cotton associated with it.
In the step which is repeated the cotton is engaged or snagged by the teeth of rotating saws and beat against bars. This beating frees the cotton from trash. The saws on which the cotton is engaged are rotating so the trash is thrown outward by centrifugal force. The heavier trash is thrown farther away from the saw cylinders.
The cleaned cotton which remains snagged by the saws is removed from the saws by means of doffing brushes. The doffing brushes rotate in the opposite direction of the saws. Once the clean cotton is removed from the saws, it is forwarded through a chute for further processing.
The trash which is expelled at the first level still has reclaimable cotton mixed with it. This trash is forwarded toward reclamation saws and associated beater bars. Once again the cotton is snagged by saws on one of the rotating saw cylinders and is beat against the bars. In this manner, the cotton is separated from the trash which is once again expelled. This process is most often repeated twice more, i.e., the trash is exposed to saw cylinders so that cotton may be engaged by rotating saw cylinders four times and beat against bars four times. After each cleaning step, the cotton is removed to a clean cotton chute and the refuse is further processed except for the final step. In effect, cotton is pulled or separated from the same trash four times. The total efficiency of the cleaning process is clearly limited by having to separate cotton from the same trash time after time.
An average bale of seed cotton which is brought to a gin weighs about 1,900 pounds. Of this 1,900 pounds, only 500 pounds (about 25% weight) is cotton lint. About 800 pounds (40%) is seed and the remaining 600 pounds (35%) is trash. It is estimated that stick and burr machines, before our invention, removed about 250 pounds of the trash with a loss of under 1 pound of good cotton. The effort to prevent loss of cotton has resulted in incomplete cleaning. Each improvement in the cleaning process improves the grade of the ginned cotton and so ginners and manufacturers have tried for years to improve this cleaning process.